The fabrication of large expanses of flat decking or flooring by fitting together a number of rectangular modular sections is well-known in the construction art. When contiguously fitted together, each corner of each of the equally dimensioned sections meets the corners of three adjoining such sections. At these meeting points, each of the corners is conventionally secured to the others and frequently to a supporting structure or subfloor in order to prevent separation of the sections and to maintain them in place. One known manner of fastening the modular sections together, for example, has been to bolt each corner to its supporting structure. This necessarily involves the provision of four holes and four bolts for each junction of the modular section corners. Further, threaded holes must be provided in the supporting structure which precisely align with the holes in the section corners to ensure that the sections are accurately fitted together. If even one of the latter holes is slightly out of alignment, not only will the snug fitting of that corner be prevented, but the holes at the other corners of the same section will be thrown out of alignment as well. Any mechanical arrangement for individually securing the modular section corners, thus, in many cases presents the problems of alignment, the necessity for providing multiple fastening devices, and the time and care, and thus, the expense of achieving accurately fitting corner junctions. It is accordingly an objective of the present invention to provide a simplified modular planar section fastening arrangement which requires fewer parts, ensures a more accurate fit, requires less fabrication time, and realizes significant cost savings.